We have grown used to Usain Bolt the imperious dominator. Usain Bolt the record breaker. Usain Bolt the showman. But in a flash flood, and with lightning streaking across Moscow's skyline, we saw another side to the greatest sprinter of all time. Usain Bolt, the Stakhanovite labourer: gritting his teeth and grinding to victory.

This time there was no sudden spurt to leave his rivals for dead. Nor a delirious celebration afterwards. Bolt's legs, as he admitted later, were still sore from the semi-finals earlier on Sunday evening. There was, however, the lingering warmth of another world championship gold medal – his sixth in total and his second at 100m, to follow his world-record breaking triumph in Berlin in 2009.

Bolt's time of 9.77sec was his slowest in a major 100m final. But it was still a half-metre too good for Justin Gatlin, the American with the Florida swagger and doping past. He took silver in 9.85sec with Bolt's fellow countryman Nesta Carter taking bronze in 9.95 sec.

Two other Jamaicans, Kemar Bailey-Cole and Nickel Ashmeade, finished fourth and fifth with 9.98sec, and Britain's James Dasaolu was last in a time of 10.21.

Bolt said he was content but admitted he had wanted to run faster. "My legs were sore after the semi-finals, I don't know why, but the world record wasn't on so I came out just to win," he said. "Back in Jamaica, they do not expect less than that from me. They always expect me to dominate."

Gatlin claimed that he thought the final was going to be postponed because of the conditions. "We saw the lightning on the horizon when we were on the warm-up track," he said. "Then we saw the tent rattling and I thought they were going to postpone the race."

In the stadium, Bolt was asked if he knew any Russian. "The only thing I know is niet," he said to grateful cheers. "But thank you for coming to support me." He then blew imaginary kisses, but by then many of the tribunals staring back at him were blank.

At least the stadium was slightly more full than on Saturday night, when Mo Farah proudly felt precious metal on his chest and Vladimir Putin, looking as twitchy as a bouncer in a small market town, declared the championships open. Even so, the Luzhniki's vast breakfast bowl of an arena – despite being reduced in capacity from 75,000 to 35,000 – still looked half-full.

Imagine Rudolf Nureyev twirling and pirouetting to banks of sponge seats at the Kirov. Or Dmitri Shostakovich playing the Mayakovsky Operetta Theatre to piecemeal applause. Somehow it felt wrong for athletics' blue riband event to be met with such indifference.

There was much street theatre beforehand, however, with the protagonists strutting and bustling and smiling as they sought a psychological edge.

Gatlin, swarming backwards and forwards from his lane number to the blocks, was the most vocal, hollering: "'Let's go, let's go" to the TV cameras. The Frenchman Christophe Lemaitre, stiff-backed and eyes sliding from side to side, the most nervous. Dasaolu appeared to be gulping for air like an athlete unused to operating at such high altitude, which he was.

Bolt, though, was the epitome of jazz-era cool. As he was introduced the heavens opened so he pretended to whip out an imaginary umbrella and smiled. In Daegu in 2011, with Yohan Blake a clear and present danger, he had false-started before the final.

But with Blake absent through injury and Tyson Gay – who has the fastest time in 2013 – missing after testing positive there were no such reasons to be fearful in Moscow.

Bolt was out of the blocks sharply, in the same reaction time of 0.163sec as Gatlin, and although the American picked up faster and led by the width of a torso for the first 50m, Bolt was always within striking distance.

He was on terms by 50m and was ahead by 60m. But after that there was no quickening of the gears or acceleration of spectators' pulses: Gatlin remained half a metre behind until the line.

"I was never worried: I know what I am capable of," insisted Bolt. "After the semis I knew who was capable of running faster. I knew Gatlin would be the biggest rival but as long as I had him covered it was OK."

He then pledged again to do what he could to divert attention away from the numerous drugs scandals that have tainted the sport. "I want to distract people away from the bad things," he said. "I just enjoy running. I help in any way I can."

Dasaolu had looked impressive in running 9.97sec to make the final. But when he arrived there, a couple of hours later, his body had nothing left. "I got to 50 or 60m but then they just started to run away from me," he sighed. "I think the semi-final took it out of me.

"Saturday was my first time coming out of blocks in a fortnight so I knew I'd be a bit rusty," he added. "I didn't have all the training behind me."

Dwain Chambers and Harry Aikines-Aryeetey finished well down in their semi-finals. "I don't know what to say - I don't have any thoughts," said Chambers. "Being part of the world championships has been great, it's been great to be back here again and part of the team. Other than that it's disappointing."

Aikines-Aryeety described his run as "embarrassing" and "upsetting".

But when it came to the big show, at the end of Sunday night, there was thunder. There was lightning. And there was Bolt.